Flotation of minerals



UNITED STATES PATENT OFFICE.

CLEMENT L. PERKINS, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO METALSRECOVERY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

FLOTATION OF MINERALS.

No Drawing.

To all whom it may concern:

Be it known that I, CLEMENT L. PERKINS, a citizen of the United States,residing at Pittsburgh, in the county of Allegheny, State ofPennsylvania, have invented certain new and useful Improvements inFlotation of Minerals; and I do hereby declare the following to be afull, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

This invention relates to the concentration of'minerals, such as sulfidores and the like, by flotation, and is based upon the discovery thatimproved results can be obtained by carrying out the flotation operationwith the addition, to the ore or mineral pulp, of certain non-oleaginoussolid or ganic compounds, which themselves have substantially nofrothing properties, but which have valuable properties as selective orcol.- lecting or mineral-modifyin agents for the mineral. Such agents,although substantially non-frothing, nevertheless so act upon theminerals that they very .materially assist in the recovery of theminerals when used in connection with a suitable frothing agent.

Among the agents which are of particular value as selective orcollecting or mineralmodifying agents, and which are substantiallynon-frothing, are reduced compounds which are relatively easilyoxidizable such as, for example, diazo-amino-benzene. It

may be that these compounds are adsorbed at the surface of the sulfid ormineral particles, and that they so modify the sulfid or mineralsurfaces that these surfaces are less easily wet by water or made morereadily susceptible to attachment by the air bubbles. In some cases thereduced compound is apparently further reduced by the action of thesulfid particles, so that the action may partake of both a chemical andphysical nature. These agents also appear to be adsorbed to some extentby certain of the gangue particles, but in this case oxidation of thecollecting agent apparently takes place at the surface of the gangueparticles, so that the actual surface presented is an oxidizing oroxidized'surface, while in the case of the sulfid particles it appearsto be a reduced surface. However, I do not desire to limit myself by anytheoretical explana- Specification of Letters'Iatent.

Application filed July 13, 1920.

Patented Jan. 4, 1921.

Serial No. 395,997.

tion of the mechanism of the action of these collecting agents.

Although the collecting agents are substantially insoluble, and arecommonly referred to as insoluble, nevertheless, they are soluble to avery small de ree, and it appears to be by reason of thls solubilitythat they are able to act upon the minerals and exert their markedselective and collecting properties.

These collecting agents are, as above noted, non-frothing, and it is,therefore, important to supplement their actionby an agent\ which willprovide an appropriate amount of froth. The frothing agent, however, maybe entirely inadequate to perform the flotation process by itself,inasmuch as its function appears to be simply to provide bubbles insuflicient quantity and of sulficient persistency to overflow into thelaunder of the flotation machine, thereby mechanically facilitating theremoval of the mineral concentrate.

Among the collecting agents of the character above referred to, that is,which are substantially nonfrothing, are included certain of thearomatic thio-ureas, and many of the azo and diazo compounds. Acollecting agent which I have found of particular value is diazo amino-benzene, C,H,:N:NNHC H The process in which such collecting ormineral-modifying agents are used is described and broadly claimed in myprior application Serial No. 312,247, filed July 21, 1919, while themore specific claims of said prior application relateto the process inwhich the selective or collecting agent, and

the frothing agent, are added in admixture, the one dissolved in theother. The claims of the present application relate to the two-stepprocedure in which the selective or collecting agent is first intimatelyincorporated with the mineral pulp, and the frothing agent subsequentlyadded.

The collecting agent or agents can thus be incorporated with the ore ormineral pulp .1n any suitable manner which will lnsure their uniformincorporation and dissemination throughout the pulp. They may thus beincorporated with advantage by grinding in the tube mill or ball mill inwhich the ore itself is ground, and this is particularly advantageous.The action of such agent appears to be a selective modifying action uponthe mineral surfaces rather than any action of importance upon the wateritself, inasmuch as investigations indicate that the removal of thewater from the ore pulp, after the collecting agent has beenincorporated therewith, and the subsequent washing of the ore, does notdeprive it of its improved flotation properties, and it can be againmade into an ore pulp with fresh water and subjected to flotation.Investigations of this kind indicate that the collecting agents have aselective modifying effect upon the mineral surfaces and that anymodifying effect upon the water is incidental.

After the collecting agent or mineralmodifying agent has beenincorporated with the ore pulp, a suitable frothing agent is then addedand intimately incorporated. The frothing agent may be added at any timesubsequent to the incorporation of the collecting agent. It may thus beadded in the launder leading to the flotation cell, or even in the cellitself.

The flotation operation can be carried out in the common forms offlotation apparatus, such as an ordinary Callow cell, or apparatus wherethe air is incorporated in the ore pulp by mechanical agitation.

It is of advantage in many cases to add to the ore pulp a small amountof alkali,-

which may be suflicient in amount to give to the ore pulp a distinctalkaline reaction, When alkalis are used, it is desirable to give theman appreciable time of contact with the ore pulp before subjecting thelatter to flotation. When possible, it appears preferable to add thealkalis in the grinding mill, so that they will be present during thegrind ing operation. The alkali may be caustic alkali, such as sodiumhydrate, or an alkaline salt, such as sodium carbonate, or even lime orcalcium oxid or hydrate can be used.

The amount of the collecting agent added may vary somewhat, and may beas little as one-fifth or one-fourth of a pound per ton of ore, (thatis, calculated on the weight of the ore and not of the ore pulp). I haveobtained good results with the use of as little as one-thirtieth of apound per ton of ore. Larger amounts may, however, be used.

The invention will be further illustrated by the following specificexamples of tests made upon a copper sulfid ore having a siliciousgangue containing its flotable or sulfid copper in the form of a mixtureof chalcocite and chalcopyrite, that is, socalled porphyry ores, such asthose of the Utah (aopper Company. In general, treatment of the ore withalkalis, as above noted, gives improved results, the alkalis themselvesapparently having a valuable effect upon the ores in improving theflotation thereof.

1. Dz'azo-amino-benaeae and terpineol.

500 parts by weight of Utah Copper Companys ore was ground in the pebblemill with 250 parts of water, sodium hydroxid equivalent to two poundsper ton of dry ore, and diazo-amino-benzene equivalent to onefifth poundper ton. The ground pulp was 7 2. Dz'aeo-amino-Lenzenc and terpineol.

The details of the test were thesame as those of No. 1, except that theproportion of diazo-amino-benzene was reduced to onethirtieth pound :perton. The heads for test No. 2 contained1.38 per cent. copper, theconcentrate produced contained about 17.3 per cent. copper, and therecovery was about 87.7 per cent.

3. Diazamninmbeneenc and pine oil.

The details of this test were the same as those of No. 1, except thatsteam-distilled pine oil was substituted for terpineol. The proportionof pine oil used was about onefourth pound per ton of dry ore. The headsfor test No. 3 contained 1.39 per cent. copper, the concentratesproduced contained about 17.9 per cent. copper, and the recovery wasabout 88.6 per cent.

The collecting agent can with advantage be used in addition to many ofthe usual oil mixtures which are commonly employed in flotation, withresulting improvements in the flotation operation. Flotation oils or oilmixtures which are good frothing agents, such as pine oil and other wooddistillation oils, are of particular value, inasmuch as they supplementthe action of the collecting agent, and are themselves supplemented intheir ore floating properties by the collecting action ofthe collectingagent.

In the flotation of zinc-lead ores, it has been found of advantage togrind the collecting agent with the neutral ore pulp; and still betterresults have been obtained when copper sulfate and sulfuric acid werealso used in the proportion of about one pound of each per ton of dryore. A small amount of a suitable frothing agent, as above noted, shouldalso be used.

It is characteristic of the invention that the froth obtained is readilybroken up, while a relatively clean concentrate and high recovery can,nevertheless, be obtained. A part of the collecting agent, together witha part of the frothing agent, can sometimes be recovered so that theyare available for use in the treatment of further amounts of ore; forexample, by recovering the circuit water from the concentrates, or eventhat from the tailings, and returning the same to the process, withresulting economy in the amount to be added for subsequent operations.The amount of the collecting agent can, however, in many cases bereduced to such a small amount that it is feasible to practise theinvention Without such recovery of the agents employed.

The addition of the flotation agents successively has the advantage thatthe grinding of the ore pulp and the preliminary incorporation of'thesubstantially non-frothing collecting agent can be effected withoutanyobjectionable froth formation, and the ore pulp can thusbe kept freefrom objectionable froth formation until the frothing tion of mineralsby flotation, which com-' prises grinding the ore with the additionthereto of a small amount of a substantially non-frothing,non-oleaginous organic mineral collecting agent, subsequently adding asmall amount of an agent having good frothing qualities, and subjectingthe resulting mixture to a flotation operation; substantially asdescribed.

3. The method of effecting the concentration of copper ores byflotation, which comprises intimately incorporating with the ore pulp asmall amount of alkali and a small amount of a substantiallynon-frothing, nonoleaginous organic mineral collecting agent,subsequently adding an agent having good frothing qualities, andsubjecting the resulting mixture to a flotation operation; substantiallyas described.

4:. The method of effecting the concentration of copper ores byflotation, which comprises grinding the ore in admixture with a smallamount of alkali and a small amount of a substantially non-frothing,non-oleaginous organic mineral collecting agent, subsequently adding asmall amount of an agent having good frothing properties, and subjectingthe resulting mixture to a flotation operation; substantially asdescribed.

The method of effecting the concentration of minerals by flotation,which comprises adding to the mineral pulp a small amount ofdiazoaminobenzene, subsequently adding an agent having good frothingproperties, and subjecting the resulting mixture to a flotationoperation; substantially as' described.

6. The method of effecting the concentration of minerals by flotation,which comprises grinding the ore with the addition thereto of a smallamount of diazoaminobenzene, subsequently adding a small amount of an aent having good frothing qualities, and su jecting the resulting mixtureto a flotation operation; substantially as described.

7. The method of effecting the concentration of copper ores byflotation, which comprises intimately incorporating with the ore pulp asmall amount of alkali and a small amount of. diazoaminobenzene,subsequently adding an agent having good frothing qualities, andsubjecting the resulting mixture to a flotation operation; substantiallyas described.

8. The method of effecting the concentration of copper ores byflotation, which com prises grinding the ore in admixture with a smallamount of alkali anda small amount of diazoaminobenzene, subsequentlyadding a small amount of an agent having good frothing properties, andsubjecting the resulting mixture to a flotation operation; sub- 95stantially as described.

In testimony whereof I afiix my si nature.

CLEMENT L. PERI INS.

